Large off-highway machines, such as mining trucks, are known to employ electric drive propulsion systems to propel or retard the machine. Typically, an electric drive propulsion system includes an alternator, or other electrical power generator, driven by an internal combustion engine. The alternator, in turn, supplies electrical power to one or more electric drive propulsion motors connected to wheels, or other ground engaging elements, of the machine. Some of these large mining trucks are also configured to receive electrical power from an overhead trolley line. Specifically, at mining sites having overhead trolley lines installed, a pantograph, or other similar device, coupled with the mining truck may be moved into electrical contact with the overhead trolley line. When engaged, the pantograph enables electrical power from a substation to be drawn from the overhead trolley line and used to power the electric drive propulsion motors. Typically, the overhead trolley line may be used to power the electric drive propulsion motors when the mining truck, or trolley capable mining truck, has a relatively high electrical power demand, such as when the mining truck is loaded and is traveling uphill.
U.S. Published Patent Application No. 2011/0094841 to Mazumdar et al. teaches an on-board electrical storage system for a trolley-based electric mining haul truck that may be used to store retard electrical energy created during dynamic braking. This stored energy, as suggested by the disclosure, may be used to supplement trolley power during an uphill haul. The Mazumdar reference also suggests that, particularly when the on-board electrical storage system is fully charged, the retard electrical energy from the wheel motors may be fed through inverters and returned to the utility grid. According to U.S. Published Patent Application No. 2011/0175579 to Mazumdar, the retard electrical energy stored in the on-board electrical storage system may be used to provide auxiliary power to components, such as computers, displays, and control systems, when the electric mining vehicle is not receiving trolley power.
The Mazumdar references introduced above primarily discuss an on-board electrical storage system for trolley-based electric mining vehicles. Although the Mazumdar references suggest particular means for reducing wasted electrical energy, there is a continuing need for alternative ways to reduce waste. Further, there is a continuing need for improved efficiency, including electrical efficiency, in the context of trolley capable mining trucks, while maintaining or improving performance and reliability.
The present disclosure is directed to one or more of the problems or issues set forth above.